Like Aprilia, Suzuki is exempt from the private testing restrictions, their only limit being the number of tyres available for the year.

The main focus of the Valencia test was to improve the traction and grip generated by the GSX-RR, with both riders trying two different chassis specifications. So far this year, they have preferred a chassis based on last year's design.

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The Suzuki engineers also tried variations in geometry, set-up configurations and changes to the electronics.

"It's been positive for us to take profit from this private test, we needed to find more efficiency with the traction and we also worked for many other improvements," said Vinales, who gave the GSX-RR its first podium at Le Mans.

"The Suzuki factory sent us many pieces to test and also new configurations, so we tried some improvements in the chassis and also many set-up configurations. It was a positive test, we had a great deal of feedback that will be useful for the future to determine the paths to take.

"The GSX-RR is already a very good machine in certain areas; like the fast corners and its agility, but lacks in some other areas. We are working to find a good balance and be more and more performing."

Vinales finished sixth at Mugello, with Espargaro in ninth.

"The Mugello weekend was tough but testing is always important for us, as we are still in the development process and we need to grow as fast as possible," said Espargaro. "Here we had many things to test as the Factory is working very hard to give us all its support.

"We had two different steps on the chassis and one of them gave me very positive feeling, so we have made another step forward. Of course we need to further investigate our options; in Barcelona we will continue this work, but it is very positive that we have this support and we are consistently improving."

No lap times were released by Suzuki.

Vinales is leaving for Yamaha at the end of the year, while Espargaro's future is yet to be decided, with Andrea Iannone the only confirmed 2017 Suzuki MotoGP rider.